In beer-taste beverages, raw materials such as malts and hops greatly affect their qualities. For example, hops not only give bitterness to beer-taste beverages but also give refreshing hoppy aroma and a body. Bitterness is attributable to an α-acid in the hops, hoppy aroma attributable to terpenes, and a body attributable to polyphenols, and the like, so that each of them is attributable to various ingredients. Accordingly, the bitterness, the hoppy aroma, and the body of the beer-taste beverages have been conventionally adjusted by selecting the methods of brewing, varieties to be used, and processed products depending upon the hops used.
As the selection of the methods of brewing, when hops are added to a wort boil, quality can be controlled by adding the hops at an initial stage, adding the hops in an intermediary stage, or adding the hops at a second-half of a wort boiling step or after a fermentation step. When added at an initial stage, an α-acid attributable to bitterness is sufficiently isomerized, so that high-quality bitterness can be extracted. On the other hand, a majority of the terpenes attributable to aroma would evaporate away. When added at a second-half stage, the terpenes attributable to aroma would remain, surely giving a hoppy aroma; however, on the other hand, isomerization of an α-acid would be insufficient, so that the bitterness may possibly not harmonize with the beer. In addition, other methods include dry hopping in which hops are dipped in a fermented and stored liquor. In the case of dry hopping, a fresh aroma distinctively owned by raw hops is given.
As the varieties to be used, hops are roughly classified into bitter varieties having a high α-acid content mainly purposed in giving bitterness, and aroma varieties giving high-quality aroma, and varieties of over 100 are being cultivated in the global markets. By selecting varieties having diversified qualities on these bitterness, aroma and body, a desired beer-taste beverage can be made and developed.
The processed products are “dry hop flowers” in which the hop flowers are simply dried after the harvest; “hop pellets” in which dried hop flowers are pulverized and pelletized; or “a hop extract” in which only a bitterness ingredient or a polyphenol ingredient is extracted from the hop pellets. By using these processed products according to their purposes, a desired beer-taste beverage can be made and developed.
However, since the hops are agricultural products, it is understood that the quality differences are caused by cultivation factors. Therefore, in actual situations, it is difficult to stably develop a desired quality simply by selecting the methods of brewing, varieties to be used, and processed products. Therefore, the elucidation of the influences of the cultivation factors on the qualities of the hop raw materials would be important to stably develop and make a beer-taste beverage having a desired quality with excellent accuracy.
The cultivation factors which are considered to influence the hop qualities include the followings: Basic factors such as soils, human factors such as methods of cultivation, climactic factors such as temperature and rainfall, and the like. It can be found with the senses that the cultivation factors as listed herein influence the qualities of hops; meanwhile, for example, it has been confirmed in Non-Patent Publication 1 that as to the Saaz hops, the analysis of the climates at plant year age and an α-acid, which is a bitterness ingredient, has been carried out. It has been confirmed from the data that the values of the α-acid, which is the bitterness ingredient, are greatly fluctuated by the climactic factors such as temperature, humidity and the number of sunshine days.
On the other hand, Patent Publication 1 discloses a method of controlling the qualities of bitterness ingredients of hops by coming up with methods of storing hops after the harvest or methods of fermentation thereof.